Ageing of ion-exchange membranes in electrodialysis: A structural and physicochemical investigation

摘要: Abstract Understanding the ageing mechanisms of ion-exchange membranes (IEMs) used in electrodialysis (ED) for food industry applications constitutes a major challenge. In this regard, four (two cationic ones and two anionic ones) were analyzed at end their useful life (2 years ED operation) compared with respective fresh new samples to assess evolution structural physicochemical characteristics, explore deterioration. The conductivity, capacity, water content, contact angle counterion transport number determined each membrane. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX), FTIR analyses also performed. cation-exchange (CEMs) suffered significant degradation; nonetheless, they generally more robust resistant than anion-exchange counterparts, which unstable. A degradation polymer matrix both membrane types was found. Both CEMs (AEMs) lost part sites, specific electrical conductivity decreased. However, became denser lower content higher surface hydrophobicity, while thickness AEMs increased about times. permselectivity decreased, that AEM analogues not modified. model schematically describing time structure properties built on basis microheterogeneous experimental data. main idea present colloid aggregates adsorbed by as nanoparticles occupying pores. This explain variation totality equilibrium properties, particular, apparent contradiction between loss capacity increase AEMs.